The expansion of intensive livestock production systems in developing countries
has increased the introduction of highly productive exotic breeds facilitating indiscriminate
crossbreeding with local breeds. In this study, we set out to investigate the
genetic status of the Vietnamese Black H’mong pig breed by evaluating (1) genetic
diversity and (2) introgression from exotic breeds. Two exotic breeds, namely Landrace
and Yorkshire used for crossbreeding, and the H’mong pig population from
Ha Giang (HG) province were investigated using microsatellite markers. Within
the province, three phenotypes were observed: a White, a Spotted and a Black
phenotype. Genetic differentiation between phenotypes was low (0.5–6.1%). The
White phenotypes showed intermediate admixture values between exotic breeds
and the Black HG population (0.53), indicating a crossbreed status. Management
practices were used to predict the rate of private diversity loss due to exotic gene
introgressions. After 60 generations, 100% of Black private alleles will be lost. This
loss is accelerated if the admixture rate is increased but can be slowed down if the
mortality rate (e.g., recruitment rate) is decreased. Our study showed that a large
number of markers are needed for accurately identifying hybrid classes for closely
related populations. While our estimate of admixture still seems underestimated,
genetic erosion can occur very fast even through indiscriminate crossbreeding.

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en

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Blackwell Publishing

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dc.subject

Admixture

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dc.subject

crossbreed

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dc.subject

exotic

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dc.subject

hybrids

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dc.subject

pig

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vietnam

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dc.title

Uncontrolled admixture and loss of genetic diversity in a local Vietnamese pig breed